Patients randomized in "PREOXYFLOW" group will received a four minutes preoxygenation period with Nasal High Flow Therapy (HFT) (60 l/mn FIO2 = 1) before orotracheal intubation under laryngoscopy after crash induction. Patients randomized in "STANDARD FACE MASK" group will received a four minutes preoxygenation period with standard face mask (15 l/mn) before orotracheal intubation under laryngoscopy after crash induction